we had a million trucks in america in 1956. we have over seven million trucks on our highways today. our economy depends on mobile, on movement of people and goods. the interstate highway system and the national highway system that have fundamental reasons for which our economy has expanded at the reality it has grown. ... >> that thereby for shock absorbers and more tires and other equipment for their vehicles. where we improve the roadway, where we make it more efficient and safer and save lives, we are improving our economy. the highway trust fund is different from other government investments. that's what i'm saying. and so with the aviation program. >> can i add something? i'm not a transportation expert, but i bet a lot of reports about transportation funding, and i remember in particular a pretty groundbreaking report produced by the urban institute in 2004, i believe, where they actually looked at the economic literature on transportation spending. and acknowledged that for very, very long, in fact, economists agreed th